Devices for preparing a beverage by injecting pressurized fluid into a capsule are well-known, especially in the field of producing coffee or coffee type beverages. In addition, other comestible ingredients such as chocolate or milk products can be contained within the capsule. By means of an interaction of these ingredients with a liquid, a beverage such as coffee, tea or other comestibles, such as for example soup, can be produced. The interaction can be for example an extraction, brewing, dissolution, etc. process. Such a capsule is particularly adapted to contain ground coffee in order to produce a coffee beverage by having hot water under pressure enter the capsule and draining a coffee beverage from the capsule.
Systems and methods for obtaining fluid comestibles from substances containing capsules are for example known from EP-A-512470 (counterpart of U.S. Pat. No. 5,402,707).
The principle of the extraction process as described in the prior art can be summarized as follows.
A capsule filled with beverage ingredients is inserted in a dedicated chamber of the system in which water injection means are provided which enable to inject water into the capsule. In the chamber, dedicated opening means are provided which generate at least one opening in a first wall of the capsule. Accordingly, water entering the capsule through the opening in a first wall is made to interact with ingredients contained in the capsule while traversing the interior of the capsule and is then made to leave the capsule through at least one opening/perforation provided in a second wall of the capsule. As a result of the interaction between water and the ingredients in the capsule, a beverage or other comestible can be produced.
It has been found that during a lifecycle of a beverage preparation device to be used in conjunction with such a capsule, irregularities such as a slightly different closing force due to bearing play or even small ridges or grooves in a dedicated enclosing member of such a device are likely to be present respectively to occur. Moreover, irregularities may also be provided on purpose for facilitating removal of the capsule from the beverage producing device and/or improving the force distribution on the capsule and reducing the force required for closing the device onto the capsule. Hence, small ‘leaks’ may be present during the enclosure of a capsule in a dedicated beverage producing device. Thereby, any ‘leak’ at the exterior of the capsule reduces the pressure build-up inside the capsule. On the other hand, it is well known that a sufficient extraction pressure is a key factor for the quality of espresso-style coffee.
Accordingly, different pressure drops within the capsule may occur if the capsule is used in conjunction with different beverage production devices. This however might not be easily anticipated by the user and it however will negatively affect the sealing properties of the dedicated enclosing members of a beverage production device.
Therefore, the present invention aims at providing enhanced sealing properties for such a capsule in order to compensate for different kinds of pressure drops within the capsule and thus, enable effective sealing of the capsule during beverage preparation.
From the prior art sealing means provided at a capsule to be used in conjunction with a beverage production device are already known. In general, these capsules have sealing means additionally applied to an outer surface of the capsule. However, said sealing means suffer the disadvantage that they are not sufficiently integrated to the structure of the capsule and potentially protected from external constraints. Consequently, the sealing effect at the end can be affected. For example, the sealing means can be peeled off from the capsule body due to external influence or wear and tear. The capsule may also show quality issues during mass production, for example, forming seal thicknesses having inconsistent sizes and shapes. Accordingly, a capsule sealing arrangement is sought-after which does not suffer said disadvantage.